Climate change is the biggest health threat of this century

Reducing emissions means protecting our health: if unmitigated, climate change will pose increasingly severe challenges to human well-being.

The effects of climate change, such as changes in precipitation patterns, more intense droughts and heatwaves, sea-level rise and stronger hurricanes, will impact human health with increasing force, affecting people all over the globe. In the United States alone, the health costs of climate change and air pollution currently surpass 800 billion US dollars a year and are destined to continue rising, according to the report released earlier this year The Costs of Inaction.

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Air pollution in the US city of Los Angeles © David McNew/Getty Images

Climate change and its impact on health

The Pan American Health Organisation defines deaths, diseases and injuries caused by extreme weather events such as heatwaves, droughts, tornadoes, floods and hurricanes as the direct impacts of climate change on human health. These are felt with varying intensity depending on people’s age, gender, health and socioeconomic status, and place of residence.

2020 was the second warmest year out of the 141 ones on record according to the US National Oceanic and Atmospheric Administration’s 2020 Annual Climate Report, and since 1880, annual land and ocean temperatures combined have increased per decade at an average rate of 0.08 degrees Celsius. Furthermore, since 1981, the average rate of increase has more than doubled to 0.18 degrees.

Exposure to high temperatures can cause heat stress conditions like heat stroke, heat exhaustion and heat cramps: the Climate Coalition 2021 Health Report states that in the United Kingdom, almost 12 million people are vulnerable to summer heatwaves. And global warming is also facilitating the transmission of vector-borne diseases, as the ectotherms (animals that are dependent on external sources of body heat) that carry them thrive in a warmer climate. For instance, it’s estimated that in South America, the number of people at risk of contracting malaria will rise from 25 million in 2020 to 50 million by 2080.

In addition, the heightened intensity of floods and extreme precipitations increases the risk of water-borne diseases. Floods also cause loss of human life and damage to property, threatening about 1.47 billion people worldwide who are vulnerable to inundation depths of over 0.15 metres.

The cost of the climate-induced health crisis

Worldwide, the direct damage costs to health will amount to between 2 and 4 billion US dollars per year by 2030, the World Health Organisation estimates, with climate change causing about 250,000 additional deaths per year between 2030 and 2050 as a result of diarrhoea, heat stress, malaria and malnutrition alone.

The climate crisis and its impact can severely strain healthcare systems and increase public costs. For example, in Canada, in a low global greenhouse gas emissions scenario, the cost of heat-related productivity losses will go from 3.9 billion to 5.4 billion Canadian dollars (3.3 billion to 4.3 billion US dollars) by mid-century. At the same time, the economic impact of heat-related deaths will rise – from 3 billion to 3.9 billion Canadian dollars (2.4 billion to 3.3 billion US dollars) – and so will the cost of the illnesses caused by ground-level ozone pollution, which will reach 352 million Canadian dollars (283 million US dollars).

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As well as loss of human life and damage to property, floods increases the risk of water-borne diseases © Spencer Platt/Getty Images

In Europe, the cost of additional mortality caused by climate change is expected to reach about 12 billion euros (14.2 billion US dollars) per year by the end of the century in the IPCC’s A1B scenario, in which a balance across all energy sources is reached in the context of a “future world of very rapid economic growth, and the rapid introduction of new and more efficient technologies”.

Overall, just 20 countries emit more than 80 per cent of all current greenhouse gas emissions. If they decarbonise their economic, energy, food and transport systems, not only would this contribute to mitigating the climate crisis, but global health and well-being would improve.

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